DNA Structure and Replication Quiz
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Questions and Answers

What chemical bonds must be broken to separate the two DNA strands during replication?

  • Hydrogen bonds (correct)
  • Ionic bonds
  • Phosphodiester bonds
  • Covalent bonds

Which base is exclusively found in DNA and not in RNA?

  • Guanine
  • Thymine (correct)
  • Uracil
  • Cytosine

If RNA polymerase is malfunctioning, which of the following will occur?

  • Amino acids will not be joined to tRNA
  • mRNA will not be formed (correct)
  • mRNA cannot bind to rRNA
  • One of the subunits of rRNA will not be transcribed

During transcription, DNA serves as a template for the formation of which molecule?

<p>mRNA (D)</p> Signup and view all the answers

Which of the following processes occurs in the cytoplasm of a cell?

<p>Translation (A)</p> Signup and view all the answers

What is the correct flow of genetic information according to the central dogma of molecular biology?

<p>DNA to RNA to protein (D)</p> Signup and view all the answers

Which type of RNA is responsible for transferring amino acids to the ribosomes?

<p>tRNA (D)</p> Signup and view all the answers

What happens to the strands of DNA before transcription can occur?

<p>Both DNA strands must be separated (B)</p> Signup and view all the answers

Which of the following correctly describes the pairing of nitrogenous bases in DNA?

<p>A pairs with T and C pairs with G (B)</p> Signup and view all the answers

What components make up the rungs and sides of the DNA ladder?

<p>Nitrogenous bases make the rungs; sugar-phosphate molecules make the sides (B)</p> Signup and view all the answers

Which process is specifically referred to as semiconservative?

<p>DNA replication (C)</p> Signup and view all the answers

How do tRNAs recognize the correct codons on the mRNA?

<p>The anticodon of tRNA pairs with the codon of mRNA via complementary base pairing (D)</p> Signup and view all the answers

Which enzyme is responsible for unwinding DNA during replication?

<p>Helicase (D)</p> Signup and view all the answers

If an organism's DNA contains 18% adenine, what percentage of guanine would it contain?

<p>9% (A)</p> Signup and view all the answers

Given 28% adenine and 22% guanine in DNA, what percentage of cytosine nucleotides is present?

<p>22% (B)</p> Signup and view all the answers

DNA replication is termed semiconservative because

<p>One new strand pairs with an old strand in each new double helix (B)</p> Signup and view all the answers

Flashcards

DNA transcription

The process of copying DNA information into mRNA.

Chargaff's rules

In DNA, adenine always pairs with thymine, and guanine always pairs with cytosine.

DNA structure

DNA is a double helix, shaped like a twisted ladder; the rungs are nitrogenous bases, and the sides are sugar-phosphate molecules.

Semiconservative replication

DNA replication where each new DNA molecule contains one original strand and one newly synthesized strand.

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Complementary base pairing

tRNA anticodons pair with mRNA codons to ensure the correct amino acid is added during protein synthesis.

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DNA helicase

The enzyme that unwinds the DNA double helix during replication.

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DNA Replication

The process of creating an identical copy of a DNA molecule

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Chargaff's rule example calculation

If adenine is 28%, then thymine is also 28%. The remaining 22% for guanine means cytosine is also 22%.

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Hydrogen Bonds

The weak chemical force holding the two DNA strands together.

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RNA vs. DNA

RNA is single-stranded, while DNA is double-stranded.

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Thymine (DNA)

A nitrogenous base found in DNA, but not in RNA.

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Transcription

The process of creating mRNA from a DNA template.

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mRNA

The intermediate messenger in protein synthesis, carrying the genetic code from DNA to ribosomes.

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Translation

The process of building a protein from the mRNA code.

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Central Dogma

The flow of genetic information: DNA → RNA → Protein.

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Study Notes

DNA Transcription and Replication

  • DNA is transcribed into mRNA, not amino acids
  • RNA is not transcribed into amino acids
  • mRNA, rRNA, and tRNA are transcribed from DNA
  • The process where DNA makes a copy of itself is called DNA replication.
  • Each DNA strand has one old strand and one new strand in the new DNA strand after replication (semiconservative replication).

Chargaff's Rules

  • Adenine (A) pairs with Thymine (T)
  • Guanine (G) pairs with Cytosine (C)

DNA Structure

  • DNA is shaped like a twisted ladder.
  • The rungs of the ladder are nitrogenous bases (A, T, G, C)
  • The sides of the ladder are sugar-phosphate molecules

DNA Replication

  • The term semiconservative refers to DNA replication.
  • Helicase unwinds the DNA double helix during the first step of replication.

Translation

  • tRNAs carry amino acids to ribosomes.
  • tRNAs bind to mRNA using complementary base pairing between the tRNA's anticodon and the mRNA's codon.

Genetic Information Flow

  • Genetic information flows from DNA to RNA to protein (central dogma).

RNA Structure

  • RNA is single-stranded, unlike DNA which is double-stranded.
  • RNA contains uracil (U), instead of thymine (T) found in DNA.

Enzyme Roles in Replication

  • DNA polymerase replicates DNA
  • DNA ligase joins DNA fragments after replication
  • Topoisomerase relieves tension during unwinding of DNA

DNA Composition

  • If DNA has 18% adenine, it has 18% thymine, with that being 36% of the DNA composition meaning there is 64% guanine and cytosine
  • If DNA has 28% adenine and 22% guanine, it has 22% cytosine meaning there is 56% of adenine and guanine in DNA.

Transcription vs. Replication

  • DNA replication makes a copy of the entire DNA strand.
  • Transcription makes a copy of a specific segment of DNA into mRNA.

Protein Synthesis

  • tRNA transfers amino acids to ribosomes for protein synthesis.
  • Translation occurs in the cytoplasm.

mRNA Creation

  • RNA polymerase creates mRNA from a DNA template.

Process Location

  • DNA replication and transcription take place in the nucleus.
  • Translation happens in the cytoplasm.

Base Pair Change

  • An mRNA sequence UACGCUAAU is a result of a DNA sequence AATAGCGTA because adenine (A) pairs with uracil (U) in RNA.

Process Requirement

  • DNA must be unwound for both DNA replication and transcription.

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Description

Test your knowledge on DNA structure, transcription, and replication processes. This quiz covers essential concepts such as Chargaff's rules, semiconservative replication, and the roles of different RNA types. Perfect for anyone studying genetics or molecular biology!

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